add boost on mac

macx64/include/boost/metaparse/v1/cpp11/nth_of_c.hpp

@@ -0,0 +1,45 @@
+#ifndef BOOST_METAPARSE_V1_CPP11_NTH_OF_C_HPP
+#define BOOST_METAPARSE_V1_CPP11_NTH_OF_C_HPP
+
+// Copyright Abel Sinkovics (abel@sinkovics.hu)  2017.
+// Distributed under the Boost Software License, Version 1.0.
+//    (See accompanying file LICENSE_1_0.txt or copy at
+//          http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/metaparse/v1/cpp11/impl/nth_of_c.hpp>
+
+#include <boost/metaparse/v1/fail.hpp>
+#include <boost/metaparse/v1/error/index_out_of_range.hpp>
+
+#include <type_traits>
+
+namespace boost
+{
+  namespace metaparse
+  {
+    namespace v1
+    {
+      template <int N, class... Ps>
+      struct nth_of_c
+      {
+        typedef nth_of_c type;
+
+        template <class S, class Pos>
+        struct apply :
+          std::conditional<
+            (0 <= N && N < sizeof...(Ps)),
+            impl::nth_of_c<N, S, Pos, Ps...>,
+            typename fail<error::index_out_of_range<0, sizeof...(Ps) - 1, N>>
+              ::template apply<S, Pos>
+          >::type
+        {};
+      };
+
+      template <int N>
+      struct nth_of_c<N> : fail<error::index_out_of_range<0, -1, N>> {};
+    }
+  }
+}
+
+#endif
+